To help students visualize electric fields created by charged conductors of various shapes using our Electric Fields Apparatus.
Location
room 146, shelf L6, (Wimshurst machine or Static Gencon, L2), (long banana/alligator cords, side of cabinet A)
Description
If not already prepared, pour some canola oil into the Petri dish and sprinkle a small amount of grass seed evenly onto the surface. Place the dish within the 4 alignment pins, set the apparatus on the overhead projector, and insert the chosen rod shapes into the rod-holder posts and tighten thumbscrews (the shapes should be submerged for sharper images). Connect long patch cords to the ends of the brass rods with alligator clips and insert the banana plug ends into the holes on the + and � terminals on the Wimshurst machine (See first photo.) Turn the crank only enough that the seeds line up with the electric field due to their dipoles.
If you want to show students the effect of the seeds being attracted to the electrodes and getting charged, turn the crank continuously and faster for a larger voltage difference. Ask students if they can explain why the seeds go back and forth between electrodes!
Note: You can use the static Gencon in place of the Wimshurst to show only the effects of the electric field.
